Method and apparatus for anchoring bone screws and injecting many types of high viscosity materials in areas surrounding bone

ABSTRACT

An improved method and apparatus for anchoring bone screws into bones of living beings includes a cannulated screw or bone anchor that is provided with at least one discharge opening in the distal end thereof. The head of the screw is configured to receive therein a material delivery probe in sealing relationship therewith. A fluid insertion device is connected to the material delivery probe and pumps a highly viscous material through the material delivery probe and into the interior of a bone in which the distal end of the screw has been inserted. The screw can be anchored proximally in bone to prevent backpressure from dislodging the delivery cannula and aides in achieving the high pressures necessary to cause the positive effects of materials previously not injectable in the bone or surrounding areas with the current methods and apparatia.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application hereby claims priority to pending U.S.Provisional Application Ser. No. 60/799,472 filed May 11, 2006.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

BACKGROUND OF THE INVENTION

The present invention pertains to method and apparatus for anchoringbone screws into bones of living beings and injecting under highpressure materials that are high in viscosity.

One technique for inserting and anchoring bone screws relies on use ofan expandable device that is inserted into a starter cavity produced bysharp mechanical means, which may include a drill, operating theexpandable device to expand the size of the cavity, operating theexpandable device to allow the device to contract, withdrawing thedevice from the expanded cavity, pumping some quick hardening, lessviscous cement into the expanded cavity, inserting the desired screwinto the cement-filled cavity, and removing the excess cement, if any,that is displaced by the insertion of the screw. This technique has beenused in connection with screws that are inserted into the pedicle of thevertebra.

Because of the need to create the cavity to receive the cement, thisprocedure involves time and expense to create the cavity for the screwand cement. The use of a less viscous cement increases the risk that thecement will extravasate and leak into areas where it would cause harm tothe patient.

OBJECTS AND SUMMARY OF THE INVENTION

Many new biologic and non-biologic materials are being developed for usein and around areas of bone that are using highly viscous materials.These materials are highly viscous because of their chemical compositionor from the use of viscous carriers to deliver biologic materials tosites on or around bone. The areas of current use and need are on thearticular surfaces of bone, in the intervertebral spaces, vertebralbodies and bones in general. Additionally new highly viscous cements andnew techniques of vertebral body augmentation using this viscous cementhave been described which make this described apparatus and method safeand effective for anchoring bone screws as it augments vertebral bodiesor other bony structures.

It is a principal object of the present invention to provide an improvedmethod and apparatus for anchoring bone screws into bones of livingbeings by means of an apparatus that is capable of using high pressuresneeded to inject the newer high viscous materials. This same method andapparatus also can be used to inject in areas surrounding bone,materials that are not ordinarily fluid under low pressures. Suchmaterials include the biologics for nucleus replacement or repair anduse of nonbiologics for the same purposes.

It is a further principal object of the present invention to providemethod and apparatus for anchoring bone screws into bones of livingbeings involving less time and expense than conventional methods andapparatus.

It is another principal object of the present invention to provide animproved method and apparatus for introducing highly viscous materialinto the interior of a vertebral body in which it is desired to insert ascrew.

It is yet a further principal object of the present invention to providemethod and apparatus for introducing highly viscous material into thevertebral body contemporaneously with insertion of the bone screw intothe vertebra.

It is a still further principal object of the present invention toprovide a method and apparatus for anchoring bone screws into bones ofliving beings wherein a highly viscous material is introduced into thebone at pressures within the vertebral body that are lower than inconventional methods and apparatus by using ultra high pressures tointroduce slow creeping materials.

It is yet another principal object of the present invention to providemethod and apparatus for introducing highly viscous material into thegaps that have formed due to the loosening of prosthetic implants in thecortical bone of the hip, knee or shoulder.

Additional objects and advantages of the invention will be set forth inpart in the description that follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages of the invention may be realized and attained bymeans of the instrumentalities and combinations particularly pointed outin the appended claims.

To achieve the objects and in accordance with one or more of thepurposes of the invention, as embodied and broadly described herein, anembodiment of the apparatus of the present invention can include a highpressure material insertion device, a hollow feeder tube having aproximal end that is selectively connectable and disconnectable to thehigh pressure material insertion device, a material delivery probehaving a proximal end that can be detachably connected to the distal endof the feeder tube, and a cannulated pedicle screw that is provided withone or more fluid discharge openings through a distal portion thereof.The screw threads are necessary to achieve connection with the corticalcancellous bone in the pedicle which provides firm anchorage necessarywhen using high pressures in the delivery system. The distal end of thematerial delivery probe desirably can be selectively detachable andattachable in a high pressure, sealing engagement to the proximal end ofthe screw, which can have either an uniaxial head or a polyaxial head.

In one embodiment of the pedicle screw of the present invention, severalfluid discharge orifices are provided by a plurality of holes that areextending transversely from the cannula and through the body of thescrew in the distal portion of the screw. In another embodiment of thepedicle screw according to the present invention, only one set ofaligned holes are provided along one axial section of the distal portionof the screw. In still another embodiment of the pedicle screw accordingto the present invention, a single fluid discharge opening is providedby an elongated slot that extends axially along the length of the distalportion of the screw as well as transversely from the exterior of thescrew into the cannula in the central portion of the screw. In a furtherembodiment of the pedicle screw according to the present invention, oneor more of the fluid discharge holes is/are angled with respect to boththe axial and transverse directions of the screw. The angles can be suchas to direct the discharging fluid back toward the head of the screw ortoward the tip of the screw.

The fluid insertion device, such as a cement pump, desirably is providedwith a reservoir full of cementitious fluid. The flowable but viscouscementitious fluid desirably should be capable of setting to a hardenedcondition in no less than about ten minutes. The chosen cementitiousfluid desirably has a consistency and ultra high viscosity resemblingthe viscosity of a clay or PlayDoh® brand molding material. Whether thisflowable fluid includes calcium phosphate or ceramics or an highlyviscous bone cement, it will be characterized by a high viscosity thatresists travel from the anchoring site for the screw and furtherdispersion throughout the body of the vertebral body.

Before the fluid delivery probe is connected in high pressure sealingengagement to the head of the screw, the material insertion device canbe operated to fill the feeder tube with the cementitious material orfluid, until the fluid forces all of the air out the filler tube and outof the material delivery probe that can be mounted to the distal end ofthe filler tube. Before operating the fluid insertion device to pumpcementitious fluid into the vertebral body, the surgeon desirably viewsthe real time x-ray of the position of the distal end of the screwrelative to the vertebral body to determine whether the fluid dischargeopenings in the distal end of the screw are desirably positioned fordischarging the cementitious fluid.

Moreover, the invention contemplates both percutaneous andnon-percutaneous, i.e., open, embodiments of the apparatus and method.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate at least one presently preferredembodiment of the invention as well as some alternative embodiments.These drawings, together with the description, serve to explain theprinciples of the invention but by no means are intended to beexhaustive of all of the possible manifestations of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevated perspective view of an embodiment of the presentinvention shown in use with elements depicted schematically and withportions of the anatomy removed in order to reveal features of thepresent invention.

FIG. 2 is a front plan view of components of the embodiment shown inFIG. 1 with dashed lines indicating structure that ordinarily would notbe visible in the view shown in FIG. 2 due to the opacity of variousstructures.

FIG. 3A schematically represents an assembly view of components of theembodiment shown in FIG. 2 but with portions cut away and revealed incross-section.

FIG. 3B illustrates an alternative embodiment of a component of thedevice of the present invention shown partially in cross-section.

FIG. 3C illustrates a further alternative embodiment of a component ofthe present invention with portions cut away and revealed incross-section.

FIG. 3D is a cross-sectional view of a partial section of an alternativeembodiment of a component of the present invention.

FIG. 3E is a cross-sectional view of a partial section of a furtheralternative embodiment of a component of the present invention.

FIG. 4 is a view shown in partially in cross-section of the alternativeembodiment in a fully assembled view as it would be configured afterinsertion into the anatomy and ready for dispensing the fillingsubstance and with elements shown in phantom (chain-dashed lines).

FIG. 5 is an elevated perspective view of an embodiment of the presentinvention shown in use with portions of the anatomy removed in order tofeatures of the present invention.

FIG. 6A illustrates additional alternative embodiments of components ofthe present invention with portions cut away and revealed incross-section.

FIG. 6B illustrates an assembled view of portions of the componentsillustrated in FIG. 6A with one of the elements rotated 90° from theview shown in FIG. 6A.

FIG. 7 is an elevated assembly, front plan view with dashed linesindicating structure that ordinarily would not be visible in the viewshown in FIG. 7 due to the opacity of various structures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference now will be made in detail to the presently preferredembodiments of the invention, one or more examples of which areillustrated in the accompanying drawings. Each example is provided byway of explanation of the invention, which is not restricted to thespecifics of the examples. In fact, it will be apparent to those skilledin the art that various modifications and variations can be made in thepresent invention without departing from the scope or spirit of theinvention. For instance, features illustrated or described as part ofone embodiment, can be used on another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncover such modifications and variations as come within the scope of theappended claims and their equivalents. The same numerals are assigned tothe same components throughout the drawings and description.

A presently preferred embodiment of the apparatus for and method ofanchoring a pedicle screw into a vertebral body is shown in relation toFIG. 1. Initially, apparatus and method suitable for use wherein therehas been an open incision will be described. In accordance with anembodiment of the present invention, a fluid insertion device providescementitious fluid through a hollow feeder tube and thence into a fluiddelivery probe that is selectively attachable and detachable to theproximal portion of a cannulated pedicle screw. As shown in FIG. 1, anembodiment of the apparatus of the present invention can include a fluidinsertion device that is schematically represented and indicated by thenumeral 10. The discharge end 10 b of the fluid insertion device 10 isat the distal end 10 b thereof and connected to the proximal end 20 a ofthe hollow feeder tube 20. As shown in FIG. 3A, the distal end 20 b ofthe feeder tube 20 is connected to the proximal end 30 a of the fluiddelivery probe 30. The distal end 30 b of the fluid delivery probe 30 isinserted into and connected to the proximal end 42 a of the cannula 44that is defined through the central axis of the shaft 42 of a cannulatedpedicle screw 40. The distal end 30 b of the delivery probe 30 isselectively detachable and attachable to the proximal end 40 a of thecannulated screw 40.

As schematically shown in FIG. 1, the hollow feeder tube 20 has aproximal end 20 a that is selectively connectable and disconnectable tothe fluid insertion device 10. As shown in FIG. 3A for example, thefluid delivery probe 30 has a proximal end 30 a that is connected to thedistal end 20 b of the feeder tube 20.

As shown in FIG. 3A, the pedicle screw 40 has a proximal portion 40 awith a head 41 at the free end of the proximal portion 40 a and anintermediate portion 40 c connecting the proximal portion 40 a and thedistal portion 40 b. A tip 43 is provided on the free end of the distalportion 40 b of the screw 40. The pedicle screw 40 can have either anuniaxial head (FIGS. 1, 2, 3A, 3B, 3C, 5 and 7) or a polyaxial head(FIGS. 4 and 6). The uniaxial head remains fixed with respect to thecentral axis of the elongated body of the screw 40. The polyaxial headis configured to be pivotable with respect to the central axis of theelongated body 42 of the screw 40. Some examples of polyaxial heads ofpedicle screws are disclosed in U.S. Patent Application Publication No.US2005/0228385A1 and U.S. Pat. Nos. 5,474,555 and 5,554,157, which arehereby incorporated herein in their entireties by this reference. Asshown in FIG. 4, the proximal end of the shaft 42 of the screw 40defines an arcuately shaped bulb 35 that is configured to be rotatablerelative to a cavity defined in a socket 36 formed in the distal end ofthe head 41 of the screw. The bulb 35 defines a fill cavity 42 a at theproximal end of the cannula 44, and the fill cavity 42 a is configuredto receive therein the distal end 30 b of the fluid delivery probe 30.

As shown in FIG. 3A for example, the axially elongated pedicle screw 40has a cannula 44 extending axially through generally the central axis ofthe screw 40. The cannula 44 is defined by the interior surface of thesidewall 44 a of the screw. As shown in FIG. 2, the cannulated pediclescrew 40 can be is provided with one or more fluid discharge openings 45through a generally distal portion 40 b thereof. At least one fluiddischarge opening 45 extends from the cannula 44 (indicatedschematically in FIG. 2 by the dashed line) through the sidewall 44 a ofthe screw 40 in the distal portion 40 b. No discharge openings 45 areprovided through the sidewall 44 a of the shaft 42 of the screw for mostof the length of the shaft's length, as only the distal portion of theshaft is configured with any discharge openings 45

As shown in FIG. 2 for example, the discharge opening 45 of the screw 40can be configured as an elongated slot that has its longest dimensionextending generally in the axial direction. The elongated slot desirablycan be configured as a unidirectional slot that opens only through onesection of the sidewall 44 a of the screw 40 and thus permits thesurgeon to direct the discharge of cementitious fluid in a preferreddirection into the vertebral body 60. Alternatively, the slot can be athrough slot that extends completely through from one sidewall of thescrew 40 to the opposite sidewall of the screw 40. Alternatively, aplane extending through a first slot can be disposed perpendicular to aplane extending through a second slot. Alternatively, one of the slotscan be disposed at least in part, closer to the tip 43 of the screw thanany portion of the other slot.

As shown in a cross-sectional view in each of FIGS. 3B, 3C and 3D forexample, the discharge opening of the screw 40 can be configured as acylindrically-shaped bore that radially extends through the sidewall andinto the cannula. As shown in FIGS. 3B, 3C and 3D, more than one suchbore can be provided, with the number of bores determining the flow ratefrom the cannula. As shown in FIGS. 3B and 3D, a first pair of bores 45a, 45 b can be disposed with each of the bores 45 a, 45 b in the firstpair disposed on opposite sides of the screw 40 and with each bore's 45a, 45 b central axis slightly offset from the other bore's 45 a, 45 bcentral axis when viewed relative to the axial direction of the screw40. Similarly, as shown in FIGS. 3B and 3D, a second pair of bores 45 c,45 d can be disposed farther from the tip 43 of the screw 40 than thefirst pair of bores 45 a, 45 b. Each of the bores 45 c, 45 d in thesecond pair can be disposed on opposite sides of the sidewall 44 a ofthe screw 40 and with each bore's 45 c, 45 d central axis slightlyoffset from the other bore's 45 c, 45 d central axis when viewedrelative to the axial direction of the screw 40. However, the centralaxes of all four of the bores 45 a, 45 b, 45 c, 45 d desirably reside inthe same plane that includes the central axis of the screw 40.

Alternatively, as shown in FIG. 3C for example, each of a pair of bores45 e, 45 f can be disposed on the same side of the sidewall 44 a of thescrew 40 and with each bore's 45 e, 45 f central axis residing in thesame plane that includes the central axis of the screw 40. Thisconfiguration permits the surgeon to direct the discharge ofcementitious fluid in a preferred direction into the vertebral body. Oneof the bores 45 f can be disposed closer to the proximal end 40 a of thescrew 40 than the other bore 40 e.

Alternatively, as shown in FIGS. 3E and 6A for example, the dischargeopening of the screw can be configured as a cylindrically-shaped bore 45g, 45 h, 45 i, 45 j that extends through the sidewall 44 a and into thecannula 44 along a central axis that is not normal to the central axisof the cannula 44 and thus is not in a radial direction. As shown inFIGS. 3E and 6A, the bore's 45 g, 45 h, 45 i, 45 j axis desirablyextends at a 45 degree angle from the central axis of the cannula 44,which thus is at a 45 degree angle from the radius that extends from thecentral axis of the cannula 44. Other angular orientations can bechosen. Having a variety of angular orientations provides the surgeonwith maximum flexibility in accommodating the different anatomies thatare likely to be encountered.

As shown in FIGS. 3E and 6A, more than one such bore 45 g, 45 h, 45 i,45 j can be provided, with the number of bores 45 g, 45 h, 45 i, 45 jdetermining the flow rate from the cannula 44. Moreover, each of thebores 45 g, 45 h, 45 i, 45 j can be disposed on the same side of thesidewall 44 a of the screw 40 and with each bore's 45 g, 45 h, 45 i, 45j central axis residing in the same plane that includes the central axisof the screw 40. This configuration permits the surgeon to direct thedischarge in a preferred direction into the vertebral body. As shown inFIG. 3E, each bore 45 g, 45 h has an entrance orifice 55 a through theinterior surface of the sidewall 44 a that defines the cannula 44. Eachbore 45 g, 45 h has an exit orifice 55 b defined through the exteriorsurface of the sidewall 44 a that defines the cannula 44 of the screw.The exit orifices 55 b of the bores 45 i, 45 j can both be closer to theproximal end of the screw 40 than the entrance orifices 55 a formed inthe sidewall 44 a of the screw 40. One of the bores 45 g can be disposedcloser to the tip 43 of the screw 40 than the other bore 45 h.

Moreover, it is believed that when the cementitious fluid hardens, thedirection in which the fluid enters the vertebral body will result ingreater integrity of the hardened fluid in that same direction. Thus, itis desirable to direct at least one bore in the direction of the bore 45h shown in FIG. 3E that points back toward the proximal end of the screw40. In this way, the fluid directed from this bore 45 h will act in thesame manner as a fish hook barb and retard any tendency for the screw tomove out of the vertebral body. Accordingly, as shown in FIG. 6A, anadditional embodiment of the screw 400 desirably has more than one suchbore 45 i, 45 h.

To aid the surgeon in positioning the discharge opening 45, whetherslot(s) or bore(s), whether radially through the sidewall 44 a or at anangle through the sidewall 44 a, the proximal end of the screw can beprovided with one or more markers that indicate where and how thedischarge opening(s) is/are oriented so that whether the surgery is donepercutaneously or open, the desired position of the discharge opening(s)could be observed prior to introducing the cementitious material.

As shown in FIGS. 3D and 3E, in embodiments of the screw having acannula 44 that extends completely through the tip 43 of the screw 40,it may be desirable to block off the opening 43 a of the cannula 44 inthe tip 43 of the screw. In such cases, a solid steel ball 46 can beintroduced into the cannula 44 and rest on a shoulder portion 44 bwithin the cannula 44 to thereby block off the opening 43 a in the tip43 of the screw 40. This opening 43 a in the tip 43 of the screw isdesirably of a smaller diameter than the diameter of the cannula 44 inthe remaining portion of the shaft of the screw.

In accordance with an embodiment of the method of the present invention,the distal portion of the screw can be introduced through the pedicle ofa vertebra and into the vertebral body of the vertebra. This can be donein a conventional way such as using an awl and/or a punch to start ahole through the pedicle and then rotating the screw about itslongitudinal axis with a suitable implement that results in theadvancement of the screw into the pedicle due to the pitch of thethreads formed in the exterior surface of the wall that forms the shaftof the screw. Desirably, as shown in FIG. 1, the exterior surface of thewall of the shaft of the screw is provided with threads 47 that areconfigured with suitable pitch that is designed to render the screwself-tapping upon rotation of the screw.

In accordance with an embodiment of the method of the present invention,a fluoroscope desirably can be used to observe the advancement of thescrew into the vertebral body 60. When the fluid discharge opening 45 inthe screw 40 is oriented so as to direct fluid flowing out of thedischarge opening 45 in a desired direction into the vertebral body ofthe vertebra, then the advancement of the screw 40 can be stopped. Theparticular embodiment of the screw 40 will be chosen according to theparticular vertebra in which the screw 40 is to be placed.

In accordance with an embodiment of the method of the present invention,a fluid delivery probe can be provided and connected to a filler tubethat is connected to a fluid insertion device. As shown in FIG. 3A forexample, a fluid delivery probe 30 has a proximal end 30 a connected tothe distal end 20 b of the filler tube 20. As schematically shown by thearrows 21 a, 21 b, 21 c in FIG. 1, the proximal end 20 a of the fillertube 20 is connected to the fluid insertion device 10. In the embodimentshown in FIG. 3A, the fluid delivery probe 30 extends axially ingenerally the same direction as the filler tube 20 and thus is generally“in-line” with the axis of the filler tube 20.

In the embodiment of FIGS. 6A and 6B, the head of the screw 400 iscapped so as to preclude direct axial access to the cannula 44 throughthe head. Thus, access to the cannula 44 by the fluid delivery probe 300must be directed from the side of the head as shown schematically by thearrow 301 in FIG. 6A. In the embodiment shown in FIGS. 6A and 6B, theproximal end 300 a of the fluid delivery probe 300 extends axially withthe distal end 20 b of the filler tube 20. However, the distal end 300 bof the fluid deliver probe 300 extends axially generally at a rightangle to the axial direction of the filler tube 20 and thus is generally“out-of-line” with the axis of the filler tube 20. The embodiment shownin FIGS. 6A and 6B is thus adapted for use in connection with a screwhead that is not threaded on the exterior to receive a nut 50 such asshown in FIG. 3A.

As shown in FIGS. 3A and 6A, each fluid delivery probe 30, 300 definestherein a hollow channel 31, 310 that is disposed generally along thecentral axis of the fluid delivery probe. In the embodiment shown inFIG. 6A, the channel 310 forms two legs 310 a, 310 b joined by a rightangle elbow 310 c. The diameter of the channel 310 desirably is largerthan the diameter of the cannula 44 in the shaft of the screw 400, butdesirably is at least as large as the diameter of the cannula 44, whichdesirably is formed as a through bore at least as large as would befound in a 10/11 gauge injection needle (1.69 mm/0.0665 inches).However, in some embodiments, the diameter of the bore in the cannulacan be as small as would be found in a 14 gauge needle (1.628 mm/0.0641inches) or a 15 gauge needle (1.450 mm/0.0571 inches).

In the embodiment shown in FIGS. 2 and 3A, each of a pair of opposedribs 32 a, 32 b extends radially from the exterior surface of the fluiddelivery probe 30. The proximal end 40 a of the head 41 of the screw 40includes two opposed arms 48 a, 48 b that extend axially and havethreaded exterior surfaces. The surfaces of the arms 48 a, 48 b thatface one another are the interior surfaces, and each interior surface ofeach arm defines a recess 49 a, 49 b that is configured to receivetherein one of the ribs 32 a, 32 b that is defined on the exteriorsurface of the fluid delivery probe 30.

In accordance with an embodiment of the method of the present invention,the fluid insertion device 10 can be operated so as to fill the fillertube 20 and fluid delivery probe 30 with fluid so that all air is purgedfrom the filler tube 20 and the fluid delivery probe 30. Asschematically shown in FIG. 1 for example, the fluid insertion device 10can be operated to deliver cementitious fluid 62 to the filler tube andthence to the channel (not indicated in FIG. 1) of the fluid deliveryprobe 30. As schematically shown in FIGS. 3A and 6A for example, theoutlets 33, 330 of the fluid delivery probes 30, 300, respectively, aredisposed to expel into the environment, cementitious fluid and any airthat exists in the filler tube 20 and fluid delivery probe 30, 300.

In further accordance with an embodiment of the method of the presentinvention, the fluid delivery probe can be connected to the head of thescrew so as to form a high pressure seal between the fluid deliveryprobe and the head of the screw.

As embodied herein and shown in FIGS. 3A and 6A, a sealing O-ring gasket34, 340 desirably is disposed against a shoulder formed in the exteriorsurface of the fluid delivery probe 30, 300 and near the distal end 30b, 300 b thereof where the channel 31, 310 terminates in the outlet 33,330 of the fluid delivery probe 30, 300. As schematically shown in FIGS.2 and 3A, once the distal end 30 b of the fluid delivery probe 30 isinserted into the distal end 41 c of the head 41 of the screw, theO-ring 34, which is shown partially cut away in FIG. 2, is disposed atthe entrance 42 a of the cannula 44 in the head 41 of the screw 40. Thenin the embodiment shown in FIGS. 2 and 3A, a nut 50 is threaded onto thethreaded exterior surface of the proximal end 40 a of the head 41 of thescrew 40. As the nut 50 is advanced in the direction toward the distalend 40 b of the screw 40, then the two opposed arms 48 a, 48 b of thehead 41 of the screw 40 are pressed toward one another thereby lockingthe ribs 32 a, 32 b that extend radially from the exterior surface ofthe fluid delivery probe 30 into the recesses 49 a, 49 b in the arms 48a, 48 b of the head 41. The recesses 49 a, 49 b and ribs 32 a, 32 b aredesirably disposed so that when the ribs 32 a, 32 b are locked into therecesses 49 a, 49 b, then the distal end 30 b of the fluid deliveryprobe 30 and the distal end 41 c of the head 41 of the screw 40 aresealed together via the O-ring 34 so that the cementitious fluid flowsfrom the outlet 33 of the channel 31 of the fluid delivery probe 30 intothe entrance 42 a of the cannula 44 in the screw 40 rather than escapingout of the head 41 of the screw 40 and into the environment surroundingthe head 41 of the screw 40. This arrangement ensures against escape ofthe cementitious fluid where the fluid delivery probe 30 is connected tothe head 41 of the screw 40 and the outlet 33 of the channel 31 of thefluid delivery probe 30 is joined to the entrance 42 a of the cannula 44in the screw 40.

Alternatively, in the embodiment shown in FIGS. 6A and 6B, a nut 500having threads on its exterior surface, is threaded through an axiallyextending, threaded opening formed in the cap 511 of the head 510 of thescrew 400. As the nut 500 is advanced in the direction toward the distalend 400 b of the screw 400, then the forward end 500 a of the nut 500 ispressed against the back 300 c of the elbow of the fluid delivery probe300 thereby locking the fluid delivery probe 300 against movement in theaxial direction away from the distal end 400 b of the screw 400. Theexternally threaded nut 500 and the cap are desirably configured anddisposed so that when the forward end 500 a of the nut 500 is contactingthe back 300 c of the elbow of the fluid delivery probe 300, then thedistal end 300 b of the fluid delivery probe 300 and the distal end 510b of the head 510 of the screw 400 are sealed together via the O-ring340 so that the cementitious fluid flows from the outlet 330 of thechannel 310 of the fluid delivery probe 300 into the entrance 420 a ofthe cannula 44 in the screw 400 rather than escaping out of the head 510of the screw 400 and into the environment surrounding the head 510 ofthe screw 400. This arrangement ensures against escape of thecementitious fluid where the fluid delivery probe 300 is connected tothe head 510 of the screw 400 and the outlet 330 of the channel 310 ofthe fluid delivery probe 300 is joined to the entrance 420 a of thecannula 44 in the screw 400.

The fluid insertion device 10 can be provided by a screw extrudermechanism that is capable of generating pressures within the screw ashigh as 4,000 pounds per square inch. However, somewhat lower pressuresgenerated in the screw of the present invention can be used, dependingupon the viscosity of the flowable fluid that is being used and theconfiguration of the fluid discharge openings 45 in the distal portionof the pedicle screw. An example of a suitable fluid insertion device isdescribed in U.S. Pat. No. 6,783,515, which is hereby incorporatedherein in its entirety by this reference, and another example of asuitable fluid insertion device is available from Discotech MedicalTechnologies Ltd., of Herzeliya, Israel. The fluid insertion devicedesirably can be provided with a reservoir full of a flowable,cementitious fluid that is capable of setting to a hardened condition.

In accordance with an embodiment of the present invention, thecementitious fluid 62 can be chosen so that it does not begin setting upuntil about at least ten minutes after it is introduced into thevertebral body. Cementitious fluid 62 suitable for this purpose includeshigh viscosity, acrylic cement such as polymethyl methacrylate (PMMA)that is paste-like in consistency yet can be introduced through the borethat is defined by the cannula 44. The chosen fluid 62 desirably has aconsistency and viscosity that resembles the viscosity of a clay orPlayDoh brand molding material. Whether this flowable fluid includescalcium phosphate or ceramics or an highly viscous bone cement, it willbe characterized by a high viscosity that resists travel from theanchoring site for the screw and further dispersion throughout the bodyof the patient. Cementitious fluid 62 suitable for this purpose isavailable under the trade name Hi-Visco Flow and can be obtained fromDiscotech Medical Technologies Ltd. of Herzeliya, Israel.

In further accordance with an embodiment of the method of the presentinvention, the fluid insertion device can be operated to discharge fluidfrom the discharge channel of the screw and into the vertebral body. Asschematically shown by the arrows 21 a, 21 b, 21 c in FIG. 1 forexample, the fluid insertion device 10 can be operated to pump underpressure, cementitious fluid 62 from a reservoir 11 and through thefiller tube 20. As schematically indicated by the arrow 21 e, the fluidis pumped into and out of the outlet of the channel of the fluiddelivery probe 30. Upon leaving the channel of the fluid delivery probe30, the cementitious fluid travels under pressure through the entrance42 b of the cannula and through the length of the cannula 44 asindicated by the arrow 21 f. Upon reaching the discharge opening 45 thatis defined in the distal portion of the screw 40, the fluid 62 exits thescrew 40 and enters the vertebral body 60 as schematically indicated bythe curved arrows. During operation of the fluid insertion device 10,the surgeon can monitor the discharge of the cementitious fluid 62 intothe vertebral body 60 by use of a fluoroscope or other means of visualobservation.

In accordance with an embodiment of the present invention, once thecementitious fluid 62 fills the vertebral body 60 to the surgeon'sdesired extent, then the surgeon or other personnel discontinuesoperation of the fluid insertion device 10, and thereafter the fluiddelivery probe 30 is detached from the screw 40. The detachment of thefluid delivery probe 30 can proceed in reverse order of the manner ofattachment described above. A cap can be inserted into the fill cavity42 a and sealed therein by the cementitious fluid, and excess fluidremoved.

In accordance with an embodiment of the present invention, once thefluid delivery probe has been detached from the screw, support rods thencan be attached to the screw, either with or without there having been acap inserted into the fill cavity 42 a. As shown in FIG. 5 for example,each of a plurality of screws 40 is connected to a steel rod 70 and thusis connected to each other. The steel rod 70 is held in place againstthe head 41 of each screw 40 by a respective nut 50. As schematicallyshown in FIG. 5, the proximal ends of the arms 48 a, 48 b of the head 41of each screw 40 desirably can be broken off along a line of weakness 52a, 52 b that is defined transversely across each of the arms 48 a, 48 b.

Moreover, the invention contemplates both percutaneous andnon-percutaneous, i.e., open, embodiments of the apparatus and method.The percutaneous embodiment now will be described with reference to FIG.7.

According to a percutaneous embodiment of the method of presentinvention, an incision permits insertion of a metal probe, and a hole ismade through the pedicle of a vertebra in which it is desired to inserta screw 40. The proximal end 72 a of a thin guide wire 72 such as shownin FIG. 7 can be held by the surgeon and the distal end 72 b is threadedthrough the incision and into the hole in the pedicle. A cannulatedpedicle screw 40 that is configured according to a percutaneousembodiment of the present invention can be guided by the surgeon intothe hole via the guide wire 72 by threading the guide wire 72 throughthe cannula 44 that is formed axially through the screw 40. Once the tip43 of the screw 40 is seated in the hole in the pedicle, the head 41 ofthe screw 40 will protrude through the incision and reside outside thepatient's body. The guide wire 72 then can be removed.

A conventional tool can be used to rotate the screw 40, which desirablyis self-tapping, into the pedicle while a fluoroscope or similar devicecan be used to determine when the screw 40 has passed through thepedicle and is desirably located in the vertebral body 60 as shown inFIG. 1. If end opening 43 a at the tip 43 of the cannula 44 in the screw40 should be sealed before introducing the cementitious fluid 62, then asealing ball 46 is introduced into the cannula 44 of the screw 44 toseal the end opening 43 a in the tip 43 of the screw 40.

The proximal end of the feeder tube 20 is connected to the fluidinsertion device such as a cement pump. If the screw 40 has a threadedhead as shown in FIG. 7, then the mating nut 50 is placed around thefluid delivery probe 30. The distal end 20 b of the feeder tube 20 isconnected to a connector 22 that has a body that defines a hollowconduit 22 a that extends axially through the connector 22. The distalend of the body of the connector 22 can further define a threaded bore20 c that is configured to be threaded to a threaded projection 30 cthat can be formed at the proximal end 30 a of the fluid delivery probe30. The connector 22 desirably has a pair of opposed wings 23 a, 23 bradially extending from the body of the connector 22 and configured tofacilitate manually connecting the filler tube 20 to the fluid deliveryprobe 30. The cement pump then can be operated to fill the feeder tube20 with the cementitious fluid 62 until the fluid forces all of the airout the filler tube 20 and out of the fluid delivery probe 30 that ismounted to the distal end 20 b of the filler tube 20.

The distal end 30 b of the fluid delivery probe 30 carries an O-ring 34and becomes seated in the fill cavity 42 a in the head of the screw 40.The connector 22 of the feeder tube 20 can be manipulated via a pair ofopposed wings 23 thereon until the O-ring 34 is compressed and the fluiddelivery probe 30 is snugly seated into the fill cavity 42 a in the head41 of the screw 40. If the screw 40 has a threaded head 41 as shown inFIG. 7, then the mating nut 50 is threaded over the arms 48 a, 48 b ofthe proximal end of the screw 40. As the nut 50 is advanced, therecesses 49 a, 49 b in the arms 48 a, 48 b close in around the annularrib 32 formed in the distal end of the fluid delivery probe 30 and holdthe fluid delivery probe 30 snugly in the fill cavity 42 a in the head41 of the screw 40 to effect a pressure tight seal between the fluiddelivery probe 30 and the fill cavity 42 a in the head of the screw 40.

Before operating the fluid insertion device to insert the cementitiousfluid 62 into the vertebral body 60, the surgeon views the real timex-ray of the position of the distal end of the screw relative to thevertebral body to determine whether the fluid discharge opening 45 inthe distal end of the screw 40 is desirably positioned for dischargingthe cementitious fluid 62.

The various components such as the screws 40, 400, nuts 50, 500, rods70, caps 511 and screw heads 510 desirably can be made of structurallyhard materials such as metals like stainless steel or titanium orceramic or hard plastics such as PolyEtherEtherKetone (aka PEEK),provided the materials can be given or inherently have, radiographicmarkers.

While at least one presently preferred embodiment of the invention hasbeen described using specific terms, such description is forillustrative purposes only, and it is to be understood that changes andvariations may be made without departing from the spirit or scope of thefollowing claims. For example, the cementitious material enables thescrews to be inserted directly into the vertebral body without goingthrough the pedicle. Such a method would allow for anterior or lateralplacement of the screws on the vertebral body and be anchored by theinjected material.

1. A method of anchoring a screw into a vertebral body or other areasaround the bone, comprising: providing an axially elongated screw orbone anchor that is to be anchored in the proximal corticocancellousbone, said screw or anchor having a cannula extending axially throughsaid screw or anchor and having a distal portion with a tip on the freeend of said distal portion and at least one fluid discharge channelextending from said cannula through said distal portion, said screw oranchor having a proximal portion with a head at the free end of saidproximal portion and an intermediate portion connecting said proximaland distal portions; introducing said distal portion of said screw oranchor into the vertebral body of the vertebra; using a fluoroscope toobserve when the fluid discharge channel is oriented so as to directfluid flowing out of the discharge channel in a desired direction;providing a fluid delivery probe connected to a filler tube that isconnected to a material insertion device and operating said fluidinsertion device to fill the filler tube and fluid delivery probe withfluid and purging all air from the filler tube and the fluid deliveryprobe; connecting the fluid delivery probe to said head of said screw oranchor so as to form a high pressure seal between said fluid deliveryprobe and said screw or anchor; operating the fluid insertion device todischarge fluid from the discharge channel of said screw or anchor intothe vertebral body; and detaching the fluid delivery probe from thescrew or anchor and attaching a cap to the screw or anchor.
 2. A methodof introducing a high viscosity fluid into the interior of a bone of aliving organism, comprising: providing an opening through the exteriorof the bone and extending into the interior of the bone; insertingthrough the opening an axially elongated pedicle screw having a cannulaextending axially through said screw and having a distal portion with atip on the free end of said distal portion and at least one fluiddischarge channel extending from said cannula through said tip in saiddistal portion, said screw having a proximal portion opposite saiddistal portion and with a head at the free end of said proximal portion;introducing said distal portion of said screw through the opening in theexterior of the bone and disposing said distal portion of said screw inthe interior of the bone; using a fluoroscope to observe when at leastone fluid discharge channel is oriented so as to direct fluid flowingout of the at least one fluid discharge channel in a desired direction;providing a fluid delivery probe connected to a filler tube that isconnected to a material insertion device and operating said fluidinsertion device to fill the filler tube and fluid delivery probe withfluid and purging all air from the filler tube and the fluid deliveryprobe; connecting the fluid delivery probe to said head of said screw soas to form a high pressure seal between said fluid delivery probe andsaid head of said screw; and operating the material insertion device todischarge high viscosity fluid from the discharge channel of said screwinto the interior of the bone.
 3. The method as in claim 2, furthercomprising: detaching the fluid delivery probe from the screw andattaching a cap to the head of the screw to seal the cannula.
 4. Themethod as in claim 3, further comprising: after delivery of the highviscosity fluid, leaving the screw in place to aid in at least one ofbone stabilization, distraction, motion preservation or any combinationof the foregoing.
 5. The method as in claim 2, wherein the highviscosity fluid includes biologic materials.
 6. The method as in claim2, wherein the high viscosity fluid includes non biologic materials. 7.The method as in claim 2, wherein the opening is made directly into avertebral body without going through the pedicle and the screw isinserted through the opening in the exterior of the vertebral body andsaid distal portion of said screw is disposed in the interior of thevertebral body.
 8. The method as in claim 7, wherein the screw is placedeither anteriorly or laterally on the vertebral body and anchoredtherein by the discharged high viscosity fluid.
 9. The method as inclaim 7, wherein the probe and feeder tube are locked together in such amanner as to allow ultra high pressures to be used to discharge the highviscosity fluid without the risk of disconnection of the probe andfeeder tube or leakage of the high viscosity fluid being introduced intothe bone or the surrounding areas.
 10. The method as in claim 2, whereinthe diameter of the cannula is no larger than 1.69 mm.
 11. The method asin claim 2, wherein the diameter of the cannula is no larger than 1.628mm.
 12. The method as in claim 2, wherein the diameter of the cannula isno larger than 1.45 mm.
 13. The method as in claim 2, wherein the highpressure seal between said fluid delivery probe and said head of saidscrew can withstand 4,000 pounds per square inch.
 14. An apparatus forintroducing a highly viscous material into cortical cancellous bone, theapparatus comprising: a pedicle screw having a proximal end, a distalend and an elongated cannula that extends from said proximal end of saiddistal end; said proximal end comprising a head and a pair of externallythreaded arms; a material delivery probe having a proximal end and adistal end that is received in the head of the screw; a feeder tube thatis connected to the proximal end of the material delivery probe toreceive the viscous material from an insertion device, a gasket disposedbetween the head of the screw and said distal end of the materialdelivery probe; and a nut that is threadingly received on said pair ofarms to secure said gasket in the head between said distal end of saidmaterial delivery probe and the head of the screw.
 15. An apparatus asin claim 14, wherein the screw includes a polyaxial head.
 16. Anapparatus as in claim 14, wherein the diameter of the cannula is nolarger than 1.69 mm.
 17. An apparatus in claim 14, wherein the diameterof the cannula is no larger than 1.628 mm.
 18. An apparatus in claim 14,wherein the diameter of the cannula is no larger than 1.45 mm.
 19. Anapparatus as in claim 14, wherein the screw includes only one set ofaligned holes that are provided along one axial section of the distalportion of the screw.
 20. An apparatus as in claim 14, wherein the screwfurther comprises an elongated slot that extends axially along thelength of the distal portion of the screw and transversely from an outersurface of the screw into the cannula of the screw.
 21. An apparatus asin claim 14, wherein the screw includes at least one fluid dischargehole that is angled with respect to both the axial and transversedirections of the screw.
 22. An apparatus as in claim 21, wherein theangle is such as to direct the discharging fluid back toward the head ofthe screw.
 23. An apparatus as in claim 21, wherein the angle is 45degrees from the central longitudinal axis of the screw.
 24. Anapparatus as in claim 14, wherein the proximal end of the screw isprovided with a marker indicating where the discharge opening is locatedalong the shaft of the screw.
 25. An apparatus as in claim 14, furthercomprising a plug disposed in said cannula so as to block the opening inthe tip of the screw.
 26. (canceled)
 27. An apparatus as in claim 14,wherein the material delivery probe defines a hollow channeltherethrough and having a distal end and a proximal and, wherein thedistal end and the proximal end of the hollow channel of the materialdelivery probe are not axially aligned.
 28. An apparatus as in claim 27,further comprising: a cap formed on a head formed on a proximal end ofsaid screw, said cap defining therethrough an axially extending,threaded opening; a gasket disposed between the distal end of the fluiddelivery probe and the head of the screw; a nut having threads on itsexterior surface and threaded through said axially extending, threadedopening formed in the cap of the head of the screw, said nut pressingagainst the proximal end of the fluid delivery probe thereby locking thefluid delivery probe against movement in the axial direction away fromthe distal end of the screw so as to seal the distal end of the fluiddelivery probe and the head of the screw via the gasket so that thecementitious fluid flows from the outlet of the channel of the fluiddelivery probe into the cannula in the screw without escaping out of thehead of the screw and into the environment surrounding the head of thescrew.
 29. An apparatus as in claim 14, wherein each of said pair ofarms defines a recess on an inner surface thereof.
 30. An apparatus asin claim 29, wherein the material delivery probe further comprises pairof ribs that each extend radially and into a recess in one of said pairof the arms to seal the distal end of the fluid delivery probe and thedistal end of the head of the screw by compressing said gasket when thenut is rotated and distally advanced over said arms.
 31. The apparatusas in claim 14, wherein the distal end of the material delivery probecomprises a narrowed distal end that mates with a fill cavity in thehead of the screw.
 32. The apparatus as in claim 30, wherein said armsof the said head are pressed together as the nut is advanced towards thedistal end of the screw.